Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Mixing of two or more solid polymers; mixing of solid...
Reexamination Certificate
1999-02-23
2001-01-16
Short, Patricia A. (Department: 1712)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Mixing of two or more solid polymers; mixing of solid...
C528S288000, C528S290000, C528S291000, C524S602000
Reexamination Certificate
active
06174965
ABSTRACT:
The present invention relates to a novel polyester resin which is excellent in dispersion stability of pigments and inorganic powders, and to a process for its production and its use.
Polyester resins have been used in a wide variety of technical fields, for examples, coating materials, inks, adhesives and the like. In such use, polyester resins are often used as resin for dispersion of pigments or inorganic powders. However, when conventional polyester resins are mixed with certain kinds of pigments or inorganic powders to form dispersions, there arise the problems of coagulation of pigment and increased viscosity during production or storage. Such a dispersion, if incorporated into a coating or ink composition, not only adversely affects storage properties, coloring property and workability of the composition but also forms coating film with unsatisfactory properties in weather resistance, chemical resistance and the like.
In view of the above problems, there have been proposed a coating composition and an ink composition, each prepared with the use of a sulfonic acid metal base-containing polyester resin having excellent pigment dispersibility (Japanese Unexamined Patent Publications Nos. 210960/1983 and 26070/1985). According to these compositions, a polar group introduced to polyester resin, namely, sulfonic acid metal base inhibits pigment particles from coagulation in the composition, thus giving high storage stability and forming coating film with excellent characteristics in gloss, weather resistance, water resistance, chemical resistance, etc. However, when sulfonic acid metal base-containing polyester resin is used with some kinds of pigments and basal resins for coating compositions, inferior coloring property may result.
Under the circumstances, there has been awaited the development of a polyester resin which is capable of fully dispersing a wide variety of pigments and inorganic powders to form stable dispersions.
An object of the present invention is to provide a novel polyester resin which is capable of fully dispersing a wide variety of pigments and inorganic powders to form stable dispersions, and to provide a process for its production.
Another object of the present invention is to provide a pigment dispersion and a coating composition, each containing the above polyester resin as resin for pigment dispersion.
Other objects and features of the present invention will become apparent from the following description.
The present invention provides a polyester resin having in the molecule at least one quaternary ammonium base represented by the formula
(wherein X is halogen and R is alkyl), and a process for its production.
The present invention further provides a pigment dispersion containing a pigment and the above polyester resin as resin for pigment dispersion.
The present invention also provides a coating composition containing the above pigment dispersion.
To develop the above requested polyester resin, the present inventors carried out intensive research and found that when quaternary ammonium base of formula (I) is introduced as a polar group, polyester resin is capable of dispersing a wide variety of pigments and inorganic powders better than, or as well as, sulfonic acid metal base-containing polyester resin, and that a pigment dispersion and a coating composition, each prepared using the above polyester resin are excellent in storage stability, coating workability and coloring property. The present invention has been accomplished based on these findings.
The polyester resin of the invention is prepared with the use of a polybasic acid and a polyhydric alcohol as principal starting ingredients, the polyester resin having quaternary ammonium base of formula (I) in the molecule.
In formula (I), X represents fluorine, chlorine, bromine or iodine. R represents, for example, a C
1-22
alkyl group such as methyl, ethyl, propyl, butyl, pentyl, hexyl, octyl, dodecyl or the like, among which C
1-4
lower alkyl groups such as methyl, ethyl, propyl and butyl are preferred.
The polyester resin of the invention usually contains quaternary ammonium base in an amount of 0.01 to 1 mole, preferably 0.02 to 0.8 mole, per kg of the resin solids. The above molar amount of the quaternary ammonium base was determined according to the organic sulfuric acid salt method (J. Am., Pharm. Assoc., 43, 240, 1954), which comprises adding sodium lauryl sulfate solution dropwise to chloroform solution of the test resin in the presence of Methyl Yellow as an indicator in an acidic atmosphere and calculating the amount of quaternary ammonium base from the titre.
When the quaternary ammonium base content of the resin is less than 0.01 mole, dispersion stabilizing effects on pigments tend to be low. On the other hand, more than 1 mole is likely to impair water resistance of coating film. Thus any amount outside the above range is undesirable.
The polyester resin of the invention has quaternary ammonium base of formula (I) in the molecule, more specifically, in the molecular skeleton, molecular terminal or both. Among them, it is preferable for the resin to have quaternary ammonium base in the molecular terminal.
The polyester resin of the invention usually has a number average molecular weight of 500 to 50,000, preferably 1,000 to 20,000. When the number average molecular weight is less than 500, dispersion stabilizing effects on pigments tend to be low. With a number average molecular weight over 50,000, the resin tends to have too high viscosity and is difficult to handle, hence undesirable. The resin of the invention preferably has an acid value of less than about 20 mgKOH/g.
The polyester resin of the invention has quaternary ammonium base as introduced thereto and there is no limitation on the method for its introduction.
The polyester resin of the invention may be produced by various processes. For example, the following processes (1), (2) and (3) may be preferably used for its production.
(1) A process for producing a polyester resin with the use of at least one polybasic acid and at least one polyhydric alcohol as starting ingredients, the process comprising the steps of polycondensating, together with the polybasic acid and the polyhydric alcohol, a nitrogen-containing compound represented by the formula
(wherein R
1
, R
2
and R
3
are the same or different and independently represent hydroxyalkyl, carboxyaryl, carboxyalkyl, carboxycycloalkyl, hydrogen, alkyl, cycloalkyl or aryl, provided, however, that at least one of R
1
, R
2
and R
3
represents hydroxyalkyl, carboxyaryl, carboxyalkyl or carboxycycloalkyl) to introduce amino groups to the resin, and reacting the amino groups with alkyl halide to convert some or all of the amino groups to quaternary ammonium base represented by the formula
(wherein X is halogen and R is alkyl).
Examples of alkyl groups represented by R
1
, R
2
and R
3
in formula (II) are C
1-22
alkyl groups such as methyl, ethyl, propyl, butyl, pentyl, hexyl, octyl and dodecyl, among which C
1-4
lower alkyl groups such as methyl, ethyl, propyl and butyl are preferred. Examples of cycloalkyl groups include cyclopentyl and cyclohexyl. Suitable hydroxyalkyl groups are C
1-4
hydroxyalkyl groups such as methylol, hydroxyethyl and hydroxypropyl. Suitable carboxyaryl groups are those formed by introducing a carboxyl group to a C
6-8
aryl group and include, for example, carboxyphenyl. Suitable carboxyalkyl groups are those formed by introducing a carboxyl group to a C
1-4
alkyl group and include, for example, carboxyethyl. Suitable carboxycycloalkyl groups are those formed by introducing a carboxyl group to a C
5-6
cycloalkyl group and include, for example, carboxycyclohexyl.
Examples of nitrogen-containing compounds represented by formula (II) are alkanolamines such as aminopropanol, diemthylaminomethanol, dimethylaminoethanol, dimethylaminopropanol, N-dodecylaminoethanol, N-methyldiethanolamine, 2-(N-hydroxymethylamino)ethanol, N-isobutyldiethanolamine, N-methyldibutanolamine, triethanolamine and tributanolamine; aromatic aminocarboxylic acids such as 3
Aida Haruhiko
Yamashita Fumio
Yukawa Yoshiyuki
Armstrong, Westerman Hattori, McLeland & Naughton
Kansai Paint Company Limited
Short Patricia A.
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